Generally, in a centrifuge, a sample container such as a centrifugal tube or a bottle, which contains a sample (e.g., culture fluid or blood) to be separated, is held by a rotor. The centrifuge serves to separate or purify the sample by rotating the rotor at high speed, by a drive apparatus such as a motor or the like, in a rotor chamber (rotational chamber) sealed by a door to exert a centrifugal force on the sample in the sample container.
The rotor varies in its rotational speed depending on the application thereof. A maximum rotational speed of the rotor is typically in the range from a relatively low speed of approximately thousands of rpm to a high speed of 150,000 rpm. As such, the maximum rotational speed of the rotor used in the generally provided product groups is in a wide range. Further, the various-sized centrifuges from a small centrifuge to a large centrifuge are lined up so that a capacity of the sample capable of being separated at once is in a wide range from a small capacity of several tens of ml to a large capacity of several L.
Since a large centrifugal force is required in order to perform a fast separation of the sample and the large centrifugal force is also applied to the rotor, internal stress is generated in the rotor accordingly (see JP 2005-349260 A). Manufacturers have designed centrifuges with sufficient margins so that the rotor is not broken by the internal stress or the like. However, in the IEC 61010-2-020 standard of the international standard, it is required that a test should be carried out under predetermined conditions, to ensure safety by clearing certain conditions. In this regard, many inventions relating to a protection against breakage of the rotor have been made (for example, see JP S50-56988, JP 2001-104827 A, JP 2005-230744 A, JP 2005-305400 A, JP 2005-349260 A).
For example, as shown in JP 2005-305400 A, the centrifuge includes a rotor chamber in which the rotor rotates, and a cooling pipe is often wound around the rotor chamber (sometimes, the cooling pipe is not wound). In the centrifuge with the cooling pipe being wound, the centrifuge generally has a structure in which a heat insulation layer formed with an insulating material is wound around the cooling pipe, a cylindrical protector is further disposed around the insulation layer, and a box shaped frame is formed at the outermost side. In a related-art centrifuge, a thick protector is used in accordance with a rotational energy, and by making the protector deform or rotate when the rotor is broken, energy is absorbed. Herein, to enable the protector, which is deformed by the broken rotor, to move in the rotational direction of the rotor within the frame and prevent the frame from being deformed according to the protector being deformed, there has been a need to secure a large space in the inner side of the frame in order for the protector to not be in contact with the inner surface of the frame even when the protector is deformed and rotated in the rotational direction by the broken rotor. Meanwhile, since centrifuges such as those used in laboratories or science labs are relatively large among experimental equipments, downsizing thereof has been desired by a user. Especially, since a large centrifuge among the centrifuges becomes larger in the occupied area than a small centrifuge, such desire of downsizing is particularly remarkable.